This disclosure relates to gas turbine engines having a high temperature spool with a cooling system.
A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustor section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines.
One type of compressor includes a compressor rotor assembly that has successive rows of blades, which extend from respective rotor disks that are arranged in an axially stacked configuration. The rotor stack may be assembled through a multitude of systems such as fasteners, fusion, tie-shafts and combinations thereof.
The compressor rotor assembly operates in an environment in which significant pressure and temperature differentials exist across component boundaries that primarily separate a core gas flow path and a secondary cooling flow path. For high-pressure, high-temperature applications, the components experience thermo-mechanical fatigue (TMF) across these boundaries. As temperatures increase in engines, some components' resistance to TMF may be reduced. TMF may be particularly acute immediately upstream from the combustor section where “T3” temperature limits the operating temperature of the compressor rotor assembly and, therefore, the operating efficiency of the engine.
The temperature immediately downstream from the combustor section temperature, referred to as “T4” temperature, limits the operating temperature of the turbine section and the operating efficiency of the engine as well. To mitigate thermal degradation from the extreme temperatures, some or all of the turbine stages are actively cooled by passing relatively cool air through the turbine stage. The active cooling increases the life span of the components in the actively cooled turbine stage by thermal wear. In some example gas turbine engines, the relatively cool air is drawn from a bleed located in the compressor section (referred to as a compressor bleed) and is piped directly to the actively cooled turbine section through a tangential on board injection (TOBI) cooling system.